Institute of Plant Biology and Zürich-Basel Plant Science Center, University of Zürich, Zürich, Switzerland.
Development. 2011 Aug;138(16):3409-20. doi: 10.1242/dev.060384. Epub 2011 Jul 13.
In plants, gametes, along with accessory cells, are formed by the haploid gametophytes through a series of mitotic divisions, cell specification and differentiation events. How the cells in the female gametophyte of flowering plants differentiate into gametes (the egg and central cell) and accessory cells remains largely unknown. In a screen for mutations that affect egg cell differentiation in Arabidopsis, we identified the wyrd (wyr) mutant, which produces additional egg cells at the expense of the accessory synergids. WYR not only restricts gametic fate in the egg apparatus, but is also necessary for central cell differentiation. In addition, wyr mutants impair mitotic divisions in the male gametophyte and endosperm, and have a parental effect on embryo cytokinesis, consistent with a function of WYR in cell cycle regulation. WYR is upregulated in gametic cells and encodes a putative plant ortholog of the inner centromere protein (INCENP), which is implicated in the control of chromosome segregation and cytokinesis in yeast and animals. Our data reveal a novel developmental function of the conserved cell cycle-associated INCENP protein in plant reproduction, in particular in the regulation of egg and central cell fate and differentiation.
在植物中，配子以及附属细胞是通过一系列有丝分裂、细胞特化和分化事件由单倍体配子体形成的。在有花植物的雌性配子体中，细胞如何分化为配子（卵子和中央细胞）和附属细胞在很大程度上仍然未知。在筛选影响拟南芥卵子分化的突变体时，我们鉴定了 wyrd（wyr）突变体，该突变体以牺牲附属助细胞为代价产生额外的卵子。WYR 不仅限制了卵子装置中的配子命运，而且对于中央细胞的分化也是必需的。此外，wyr 突变体还会损害雄性配子体和胚乳中的有丝分裂分裂，并对胚胎胞质分裂具有亲本效应，这与 WYR 在细胞周期调控中的功能一致。WYR 在配子细胞中上调，并编码一个假定的植物同源物的内着丝粒蛋白（INCENP），该蛋白在酵母和动物中参与染色体分离和胞质分裂的控制。我们的数据揭示了保守的细胞周期相关 INCENP 蛋白在植物生殖中的一个新的发育功能，特别是在调节卵子和中央细胞的命运和分化方面。
